The principle mechanical properties required in road stones are Satisfactory resistance to crushing under the roller during construction. Adequate resistance to surface abrasions under traffic.

1. INTRODUCTION ON AGGREGATE
CRUSHING VALUE APPARATUS
Ashian Engineers
Company India
By Er. Abhishek Sagar

2. PRINCIPLE:
The principle mechanical properties
required in road stones are
• Satisfactory resistance to crushing under the
roller during construction.
• Adequate resistance to surface abrasions
under traffic.

3. APPARATUS:
(i) Cylindrical measure and plunger
(ii) Compression testing machine
(iii) IS Sieves of sizes - 12.5mm, 10mm and
2.36mm

4. FIGURE:

5. PROCEDURES:
(i) The aggregates passing through 12.5mm and
retained on 10mm IS Sieve are oven-dried at
a temperature of 100 to 110oC for 3 to 4hrs.
(ii) The cylinder of the apparatus is filled in 3
layers, each layer tamped with 25 strokes of
a tamping rod.
(iii) The weight of aggregates is measured
(Weight 'A').

6. PROCEDURES:
(iv) The surface of the aggregates is then leveled
and the plunger inserted. The apparatus is
then placed in the compression testing
machine and loaded at a uniform rate so as to
achieve 40t load in 10 minutes. After this, the
load is released.
(v) The sample is then sieved through a 2.36mm
IS Sieve and the fraction passing through the
sieve is weighed (Weight 'B').
(vi) Two tests should be conducted.

7. CALCULATION:
• Aggregate crushing value = B/A x 100%
• The result should be recorded to the first
decimal place and the mean of the two results
reported.
• To achieve a high quality of pavement,
aggregate possessing low crushing value
should be preferred.

8. APPLICATION:
• The test can be used to asses the suitability of
aggregates with reference to the crushing
strength for various type of pavement
components.
• The aggregates used for the surface course of
pavements should be strong enough to
withstand the stresses due to wheel loads
including the steel tyre of loaded bullock-
carts

9. THANK YOU